Can I import Autodesk Inventor 2016 models?
Between Inventor and Blender you can use the .STL file format. There are also paid addons for Inventor to export in .OBJ or other types (some have free Trial).

Note that a parametric mesh from any 3D cad app will not be best suited for game engines, because the mesh will be relatively high-poly and non-optimized. You will get better results building the mesh in Blender from scratch, because you have direct control over the polygons and vertices (as opposed in CAD you have parametric control over the surfaces).

To export assemblies or parts go to File > Export > CAD Format. Choose the .STL format and under options select the polygon resolution (dicing rate) and the units the object will be exported in. You can choose either binary or ASCII file (both work).

In Blender import with File > Import > .Stl. If the option is not there, head into preferences and enable the import Stl addon which comes standard with Blender. In import options select the Y up axis. After you import the model it is good to inspect it and remove duplicite vertices -> go into edit mode (Tab), select whole mesh (A), (W) > Remove doubles. 

Here is an assembly imported into Blender: